Ar6's are known for their durability, that's half the reason I bought mine. The only issue I've heard of is top sheet chipping because it has a sidewall construction. This doesnt affect the performance of the ski it just makes it look a little less pretty. BTW your shop is retarded if they think salomon or K2 make a more durable ski.
I've noticed outside of park they hold up more like like a stiffer/wider all mountain ski and can perform well on just about anything. That being said, they are not gunna be able to charge powder as well as a fatter ski. Just saying if it snows more then a foot at my local hill, I'm defanitely going to take a fatter, all mountain orientated ski.